PHENOMENOLOGICAL INTERPRETATION OF EXCIMER-LASER ABLATION OF SINGLE-CRYSTAL OXIDES (MGO, SRTIO3 AND LAALO3)

ArF excimer laser ablation of single-crystal oxide surfaces was investigated experimentally and theoretically. All specimens (MgO, SrTiO3 and LaAlO3) showed the presence of the threshold laser fluence for the ablation, possibly suggesting a thermal process. With increase in the fluence, etching rate increased sublinearly (downwvard bowing), and with further increase in the fluence, it increased almost linearly. To interpret the ablation mechanism and this nonlinearity, we proposed the ablation model, imposing two factors (effects of laser recoil pressure and optical reflection bai the surface molten layer) to a previous dynamical model. Our proposed model explained the results well, and it was found that surface reflection by the molten layer is mainly responsible for the nonlinearity.